Braking systems have been used for many years on large vehicles such as trucks, trailers and the like. Similarly, break-away braking systems have been used for many years on towed vehicles and trailers to help stop them if they become separated from the truck cab or towing vehicle. U.S. Pat. No. 4,072,362 describes an hydraulic braking system for towing vehicle and trailer combinations. Similarly, electric braking systems have been used as shown by the electric brake controller in U.S. Pat. No. 4,721,344. Other electrical control systems for electric and hydraulic brakes are shown in U.S. Pat. Nos. 4,033,630 and 4,524,311. These systems actually combine an electrical control system with either a hydraulic braking system or an electric braking system.
Various other brake control systems such as that shown in U.S. Pat. No. 3,840,276 have been used which activate the brakes to correct for swaying in the trailer. Similarly, RE 30,550 shows such an electronic brake control circuit having a truck battery and a trailer battery which are connected in parallel.
Break-away braking systems have also been used for years as shown in U.S. Pat. Nos. 3,907,071 and 4,052,695. These systems typically have an auxiliary battery mounted on the trailer which activates the electric brakes when the trailer breaks-away or becomes separated from the truck cab. U.S. Pat. No. 3,681,551 describes a disconnect safety switch used in a break-away braking system.
Today's electric braking systems, however, suffer from a common problem in that not enough power is supplied by the control system to the electric brakes to obtain the maximum possible braking during an emergency stop. Not only must a certain amount of current be provided to the brakes but it must be provided at the proper voltage to enable the electric brakes to provide their maximum braking. Too often in emergency situations, the voltage provided to the electric brakes is insufficient to obtain maximum braking due to the resistance in the brake lines or cables.
Present braking systems often utilize standard 12-volt batteries which are also used to provide power to the other electrical components on the truck. Connecting several of these 12-volt batteries in parallel results in a power source which provides sufficient current to the electric brakes, but which is unable to provide that current at a sufficient voltage due to resistance in the brake lines from the batteries to the electric brakes. Connecting these 12-volt batteries in series would increase the voltage, but has the disadvantage that the resulting higher voltage would damage the other electrical systems of the truck which use the same batteries as a power source and which are not designed to operate using a higher voltage. However, without an increase in voltage to the electric brakes, they will be under-powered and will not provide the maximum possible braking.
A similar problem exists with today's break-away braking systems. While many of these systems use a standby auxiliary battery on the trailer which activates the trailer's electric brakes in a break-away condition and thereby slows down and stops the runaway trailer. Typically, the batteries used in break-away braking systems are 12-volts and suffer the same loss in voltage delivered to the electric brakes due to the resistance in the brake lines that the present braking systems do.
It would be desirable therefore if there was a braking system and a break-away braking system which could overcome the problems discussed above and provide the maximum braking capacity of the brakes when needed such as during an emergency stop.